resp mechanis

Question 1

During the respiratory cycle when is the intrapleural pressure most negative?

Answer 1

END OF INSPIRATION

Question 2

During the respiratory cycle when is the intrapleural pressure least negative?

Answer 2

End of expiration

Question 3

In forced expiration, accessory muscles of expiration are used. What are these?

Answer 3

These are the internal intercostal muscles & the abdominal wall
muscles (external & internal oblique muscles and the rectus
abdominis muscles)

Question 4

These are the internal intercostal muscles & the abdominal wall
muscles (external & internal oblique muscles and the rectus
abdominis muscles) Which muscles are used?

Answer 4

These are the
sternocleidomastoid and scalene muscles of the neck, and
serratus anterior and pectoralis major muscles of the chest wall.

Question 5

Why is airway obstruction in COPD and asthma most impeded during expiration?

Answer 5

Remember that the major pathology in asthma is narrowed airways. The rise in intrathoracic pressure that occurs during expiration causes increased pressure on those narrowed airways further decreasing the diameter of the airways and thus further impeding airflow through them.

Question 6

Why small airways in Emphysema? Especially on Expiration?

Answer 6

The small airways (defined as non-cartilaginous airways with an internal diameter <2 mm) in emphysematous COPD are narrowed due to the loss of elastic fibres exerting an outward pull (radial traction) on the small bronchioles. This is exacerbated during expiration. In addition, during expiration as pressure inside the thoracic cavity increases, there is increased collapse of airways directly due to the increased pressure on the airways – as these airways have little (tertiary bronchi) or no (bronchioles) cartilage to keep them open.

Question 7

Whats lung parenchyma?

Answer 7

Lung parenchyma is the portion of the lung involved in gas transfer - the alveoli, alveolar ducts and respiratory bronchioles

Question 8

COPD consists of emphysema and chronic bronchitis. what are the effects of chronic bronchitis?

Answer 8

-Increased air flow resistance– worse on expiration

– Alteration of airway surface tension(increased) predisposing to small airway collapse - worse on expiration

(Increased airway surface tension - fewer clara cells (less surfactant-like material in airways))

Question 9

Hypoxemia

Answer 9

Low arterial blood Po2

Question 10

Hypoxia

Answer 10

Low oxygen levels relative to need in body or tissues

Question 11

Right shift of oxyhaemoglobin curve means?

Answer 11

Reduced affinity therefore greater unloading